In cellular radio systems it is desirable to achieve high data rates for users also at the cell edges that typically have poor radio conditions. Traditionally, radio resources are therefore divided into different sets that are assigned to neighboring cells to make it possible to reduce the interference level for the cell edge users, thus allowing them to communicate with higher data rates, but at the cost of a reduced cell capacity. Other, more advanced methods like soft frequency reuse (sometimes also referred to as power planning) in OFDM systems or fractional frequency reuse also aim to provide users at the cell edges with higher data rates. These methods provide good ways of controlling the trade-off between cell edge data rate and cell capacity.
Previous solutions to provide high data rates to users at cell edges suffer from the disadvantage that they imply a trade-off between cell edge data rate and cell capacity. Furthermore, in many packet data systems where packets of different sizes originating from different sources, e.g. Voice over IP, web traffic etc, are transmitted from different locations in the cells in each transmission time interval, the traffic load varies significantly in both the spatial and temporal domains. The traffic variation is independent between the different cells, and the time scale of the load variations is such that the transmissions from different cells cannot be successfully coordinated.
It can thus be concluded that static resource division methods and interference coordination methods that do not take into account and utilize the traffic variations only have a limited potential.